Novel artificial silk effects and process of producing same



Patented Apr. 23, 1935 UNITED STATES PATENT OFFICE NOVEL ARTIFICIAL SILK EFFECTS AND PROCESS OF PRODUCING SAME No Drawing.

Application May 18, 1929, Serial No. 364,335. In Germany January 15, 1926 Claims.

My invention relates to novel artificial silk effects and process of producing same. The object of the invention is to provide artificial silk goods having their physical characteristics 5 changed or altered in one or more respects, such as a change in the characteristic appearance and/or hand (touch). I use the term artificial silk in this specification and in the appended claims as designating the various forms of regenerated cellulose such for example as artificial silks known as viscose, cuprammonium and nitro cellulose silks, the latter being exemplified, for example, by those known in commerce as Chardonnet and Tubize; and as excluding acetate silk.

According to the invention, for example, arti ficial silk (regenerated cellulose but not acetate silk) may be so treated that the characteristic excessive lustre of artificial silk fabrics will partially or wholly disappear and the fabric will assume a lustreless, transparent effect, and become stiffer to the touch. As will be more fully explained according to this invention, a variety of novel effects in artificial silk may be obtained, and some of these effects are especially valuable in the production of pattern effects on fabrics made entirely or partly of artificial silk fibres.

The process is applicable to artificial silk goods whether in the form of yarn (threads) or fabric (in the piece), and whether the thread or the fabric is made entirely or only partly of artificial silk.

This is a continuation in part of application Ser. No. 161,022 filed January 13, 1927. The claims in the basic or parent case are directed broadly and specifically to a process for treatment of artificial silk to modify or eliminate the altered so as to exhibit considerable stiffness of the fabric. It also includes claims to the process of using mineral acids for producing artificial silk of this character.

The ennobling of cotton fibres by means of swelling agents is known. It is possible thereby to impart upon the fibre a lustrous appearance by mercerization and to produce thereon transparent and/or wool-like effects by means of concentrated acids, according to conditions. When cellulosic material such for example as naturalcotton fibres or regenerated cellulose is acted upon by a swelling agent the swelling action or the structural change brought about in the fibre is dependent upon certain factors, i. e., concentration of the swelling agent and time of treat ment, and with most swelling agents upon the temperature of the agent, as is now well known. If the concentration is too low the swelling action will not take place in a given fibre, no matter how prolonged the time of treatment may be, and also if the concentration is suflicient to produce the desired effect on a particular fibre when applied for a suflicient time, if not applied for a suflicient time there will be .no or substantially no swelling action. Likewise utilizing a suitable concentration for the desired effect on a particular fibre, if the time of treatment is too long the particular fibre may be destroyed or spoiled. 1

As is also now understood, variations in temperature of most of the swelling agents permit of variations in one or both of the other factorsconcentration and time of treatment.

The degree of capability -of a swelling treatment to attack or alter cellulose fibres, I will designate for brevity and convenience herein as the severity of treatment. For example, if sulphuric acid of say 54 B. is allowed to act at a given temperature upon a previously mercerized cotton fabric for say 5 seconds, and a certain swelling action is obtained, the severity of such treatment will be less than one utilizing the sulphuric acid at a concentration of 58 B. and at the same temperature for the same duration; the severity of treatment being measured by the extent to which the fibres are attacked by the treatment.

Now I have discovered that swelling treatments which are of suitable severity for producing desirable swelling actions on natural cotton fibre or fabric, are too severe for the treatment of artificial silk (regerenated cellulose) and will destroy the same, but that such artificial silkcan be successfully treated with swelling agents to produce various desirable permanent effects provided the severity ,of treatment with the swelling agent is less than that capable of producing any or any substantial swelling action on the ordinary or natural cotton fibre or fabric.

While it is impossible to specify the exact factors, i. e., concentration, time of treatment and temperature, for every desired effect on the artificial silk, due to the numerous variety of effects that may be desired and the various conditions under which the artificial silk is to be treated, nevertheless, in view of the foregoing general rule taken in connection with the specific examples of treatments and other information hereinafter given, those skilled in the art will be able to determine the swelling agent and the desired factors of time, concentration and temperature for the treatment of any particular artificial silk (regenerated cellulose) for a particular finish or effect.

According to this invention valuable changes on artificial silk can be produced by means of swelling agents, whereby novel characteristics, not known before on artificial fibres, are obtained. Such swelling agents are: Alkali-hydroxide of concentrations as generally used for mercerization, i. e. of a density of above 10 B. sulphuric acid of a density of above 42 B. phosphoric acid of a density of above 50 B. muriatic acid of a density of above 20 B. nitric acid of a density of above 35 B. as well as mixtures of the above-mentioned acids; concentrated salt solutions, i. e. chloride of zinc solution of a density of above 50 B. calciumrhodanic solution of a density of above 25 B. copperoxideammonia solution with at least 0.3% copper content; but from the commercial standpoint the most desirable of these swelling agents for treating artificial silk are, caustic soda, sulphuric acid, nitric acid and the-nitration acid mixtures. Additional substances as proposed for the mitigation of the reaction can also be added to these agents; among which substances are included one and more univalent and multivalent alcohols heterocyclic bases, formaldehyde and ammonia salts.

In treating artificial silk during longer or shorter periods according to the kind and concentration of the swelling agents, and in conformity with the prevailing operating temperatures, the same loses a part of its excessive lustre and quite in contrast to the reflection of light which is otherwise predominant above everything else, it becomes transparent or translucent;

and gradually an effect develops similar to the known transparent or glass like batiste effects on cotton. If desired by .means of variations in the concentration temperature and time of action any intermediate grade between the high lustrous character of the original material and the dull, glass-like transparent, stiff, final product can be obtained.

By such treatments the artificial silk obtains new characteristics unknown before. It has been discovered that just at the beginning of the action, when no extensive swelling has taken place, and hence almost the full lustre is still present, especially in fabrics of artificial silk, an unexpected equalization ofthe fabric structure takes place, thus causing the unpleasant stripes, which very often appear in artificial silk to disappear. Also if the swelling of the artificial silk is not continued beyond the permissible measure, then. a remarkable increase of the tensile strength is observable; this is due to surface adhesion of the singlefibres or filaments.

Each of the mentioned reagents alter artificial silk in'a similar manner as above described; that is, they all act to increase the stiffness and translucency of the artificial silk fabric, and many of them to reduce or entirely eliminate the excessive lustre. But in the use of nitrating acid (a composition containing varying proportions of sulphuric and nitric acid with varying aqueous content) widely varying and different eflectsare p uceddependingupontheratiooftbenitric For example, if the nitrating acid has an aqueous content below 20%, then quite different effects are produced upon the artificial silk depending upon whether the nitric acid content or the sulphuric acid content predominates. For example if more nitric than sulphuric acid is present the result will be an entirely lustreless nontranslucent product; whereas if the sulphuric acid predominates the result will be a voluminous soft rich lustre effect of crepe-like character more nearly like natural silk. But if the nitrating acid contains 20% or more water then regardless of whether the nitric or sulphuric acid predominates, the result is similar to that with the use of the other reagents, i. e., a diminishing of the high lustre and increased stiffness and transparency.

It will thus be seen that one may produce various effects by the use of different mixtures of sulphuric and nitric acids. Such nitrated products may be subsequently treated with known denitrating means to rid them oftheir ready infiammability.

The manipulation of artificial silk is mostly carried out at normal temperature, but also low temperatures can advantageously be employed,

whereas in the use of salt solutions often the warming of agents, partially to above the boiling point of water, is necessary. The acting period can be from a few seconds to several minutes, according to the desired effect, in individual cases up to one hour. The fibre material-is held loose or under tension in the swelling agents, depending upon the effect desired.

The process is applicable to all kinds of artificial silks of regenerated cellulose, but not to acetate silk. They may be treated loose, spun or woven or as a formation of any kind, alone or also mixed with other fibres. Also those fibres, designated as staple fibre, and products obtained by spinning of short single fibres, are susceptible to this ennoblement.

Examples 1. Bleached artificial silk fabrics are passed through caustic alkali of 20 B. for a period of 4 seconds at normal temperature and slight tension, washed out, soured with diluted sulfuric acid, thoroughly washed and dried. The fabric becomes stiff, translucent, and still exhibits a faint lustre.

2. De-siz ed artificial silk is passed through a bath cooled to minus 10 C. of sulfuric acid of 49. B. during 5 seconds, washed completely free from acid and dried. The fabric becomes somewhat stifler, still shows a high lustre though slightly reduced, has become slightly translucent and appears much more uniform in structure; that is to say, the above-mentioned equalization of the fabric structure is apparent.

3. Immerse artificial silk fabrics at normal temperature during 5 minutes into nitric acid of 40 B., wash out well and dry. The fabric shows a high lustrous, translucent effect with considerable stiffness of the fabric.

4. Artificial silk yarn is impregnated for a period of 10 minutes ma nitrating acid mixture;

sistingof5partsniti'lcaciiiandlpartsulfuric acidwith an'aqucous content of 6%. then washed and dried. The fibre becomes entirely lustreless and non-translucent.

6. Artificial silk fabrics are passed througha" chloride of zinc solution of 67 B. at 40 C. during a period of 10 seconds, washed out and dried. The fabric has become translucent and has lost its lustre. Those skilled in the art will observe from a consideration of the foregoing five specific examples of treatments according to, the present invention, that in each case the factors of concentration, temperature and duration of treatment are so chosen that the severity of treatment is insufiicient to produce any or any substantial swelling action on natural cotton fibres. Taking for illustration the treatment of Example 1,--while the caustic alkali is of ordinary mercerizing strength yet the period of treatment is but four seconds at normal temperature as contrasted with the duration of treatment of from 8 to 12 seconds for mercerizing.

If the above named swelling agents are allowed to act upon localized portions of fabrics, which contain artificial silk, these portions are effected, producing contrast between treated and untreated portions, which is enhanced by dyeing due to different afiinities for certain dyes.

This fact can be of use for producing patterned eifects. can be done by laying on the same directly, by printing, blowing or painting, with or without thickening means, reserves can be applied and the fibre material consequently immersed in the swelling means. Dyestuffs can be added to the reserves, by which a local color eifect can be produced together with the reserve.

; The process can be used on all kinds of material made of artificial fibres consisting of regenerated cellulose. Materials made of artificial silk mixed with natural vegetable and animal fibres can be thereby treated.

In treating mixed materials it has been discovered, that it is advantageous for producing soft effects if the natural fibres, such for example as cotton, are workedup in the grey condition and are only cleaned or bleached after the local action of the' swelling agents thereupon. By this means the end is attained that the natural fibres, in consequence of their natural incrustations, are not so quickly affected by the swelling agents, i. e., are not affected during the time required for altering the regenerated fibres, and therefore retain their original construction. If artificial fibres and both raw and already disintegrated natural fibres are employed side by side in mixed fibres, the variety of the effects is further increased, a result that makes itself evident particularly in subsequent dyeing.

Where in the appended claims I use the term artificial silk I wish to be understood as including regenerated cellulose in the form of fibres,

threads or fabric, and whether or not, in the case of threads, they also contain cotton or other fibres; and whether or not, in the case of fabric, it also contains cotton or other threads; Also I The local action of the swelling means,

wish to be understood by the term artificial silk fabric as used in the claims, to include fabrics made either wholly of regeneratedcellulose fibres or of mixtures of same with other fibres. v

Such features of my invention as to product and process, not herein claimed, will be the subject of copending applications, Ser. Nos. 161,022 filed January 13, 1927, 364,336, 364,337 and 364,338 each filed May 18, 1929.

The term mineral acid as used in the claims is intended to include both nitric and sulphuric acids.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A process for producing a novel character of artificial silk which comprises subjecting the artificial silk to the action of a strong mineral acid represented by the-group sulfuric and nitric acids for a period of a few minutes to increase its stiffness and translucency, the temperature and concentration of said agent being sufiicient to effect said change but less than that capable of producing any substantial swelling action on natural cotton fibres during said period.

2. A process for producing a novel character of artificial silk which comprises subjecting the artificial silk to the action of a strong nitric acid for a period of a few minutes to increase its stiffness and translucency, the temperature and concentration of said agent being suflicient to effect said change but less than that capable of producing any substantial swelling action on natural cotton fibres during said period.

3. A process for producing a novel character of artificial silk which comprises subjecting the artificial silk to the action of a strong sulfuric acid for a period of a few minutes to increase its stiflness and translucency, the temperature and concentration of said agent being sufficient to effect said change but less than thatcapable of producing any substantial swelling action on natural cotton fibres during said period.

4. A process for producing a novel character of artificial silk which comprises subjecting the artificial silk to nitric acid of about 40 B. strength at normal temperature for a period of a few minutes to alter the characteristics of said silk whereby it becomes substantially stiffer and. more translucent, the conditions being such as to efiect said change but less than that capable of producing any'substantial swelling action on natural .cotton fibres.

5. Fibres composed substantially entirely of artificial silk treated by a strong mineral acid represented by sulfuric and nitric acid to increase at least one of its characteristics, stiffness and translucency, while still maintaining a high lustre, the temperature and concentration of the acid and time of treatment being sufiicient to effect said change but less than that capable of producing any substantial swelling action on natural cotton fibres.

' GEORGES HEBERLEIN. 

